Gametap has honestly had a down half-year or so, but things seem to be picking up with the THQ and Gamecock deals. It's got a great library, so I heartily endorse it.

Also, if you drink a lot of Coca-Cola products (http://www.chiefsplanet.com/BB/showthread.php?t=189168) it's worth noting that MyCokeRewards points can be used towards Gametap. One month is 99 points, and six months is 570 or something. It's a nice service for ten bucks, but even better for free.